A blood testing or medication delivery device worn on the body must have a cannula, catheter or probe properly inserted into the patient's skin to operate. Incomplete insertion may result from flexing or tenting of the skin, from incomplete insertion by the user or separation of the device from the body during use. Such devices often do not have a mechanism that enables confirmation that the delivery device is properly inserted.
As an example of a medication delivery device known in the prior art, U.S. Pat. No. 8,475,432, which is incorporated by reference, describes a medication delivery device worn on the body having an automated cannula insertion mechanism. U.S. Pat. No. 8,603,075 describes an electrochemical blood glucose probe which may be part of an apparatus worn on the body and is likewise incorporated by reference for its description of sensor/probe technology.
Percutaneous injections may be performed in the intradermal (ID) region, the subcutaneous (SC) region and the intramuscular (IM) region. For many types of injectable medications, including insulin, the SC region is preferred for administering an injection because of the blood flow through the fatty layer of the subcutaneous region. See, for example, Lo Presti, et al., Skin and subcutaneous thickness at injecting sites in children with diabetes: ultrasound findings and recommendations for giving injection, Pediatric Diabetes (2012). Alternatively, an injection may also be administered into the dermal layer. Many medication delivery devices cannot reliably ensure delivery to the SC region because of improper insertion.
If a cannula, catheter or probe is oriented at an angle with respect to the user's skin, the tip of the device may fail to reach the desired SC space after insertion.
In-vivo monitoring of blood glucose levels and the like is typically done using probes attached to an on body sensor (OBS) attached to a cannula, catheter or a probe, worn on the user's body and inserted into the user's skin at an insertion site. The ability of the probe to detect in the region of interest is greatly enabled or disabled by the ability of the user to place it in the intended location. Inserting and maintaining the probe in the desired location can often be unreliable, and users are likely to use different practices which adds to the unreliability. Installation often requires two-handed operation and can cause discomfort. Likewise, the different commercially available systems for the automatic delivery of medication, such as insulin patch pumps and infusion sets, in which a cannula is required to be inserted for continuous drug delivery, generally lack simple and reliable device feedback when the cannula is incorrectly inserted or seated at the insertion point.